Structure and method for sealing a silicon IC

ABSTRACT

Chip sealing structures and methods of manufacture are described. In an embodiment, a chip structure includes a main body area formed of a substrate, a back-end-of-the-line (BEOL) build-up structure spanning over the substrate, and chip edge sidewalls extending from a back surface of the substrate to a top surface of the BEOL build-up structure and laterally surrounding the substrate and the BEOL build-up structure. In accordance with embodiments, the chip structure may further include a conformal sealing layer covering at least a first chip edge sidewall of the chip edge sidewalls and a portion of the top surface of the BEOL build-up structure, and forming a lip around the top surface of the BEOL build-up structure.

BACKGROUND Field

Embodiments described herein relate to integrated circuit (IC)manufacture, and more particularly to sealing structure designs.

Background Information

Integrated circuit (IC) chips, or dies, are commonly provided withvarious sealing structures to provide hermetic sealing and crackprotection. In one aspect, sealing structure may protect the internalcircuits and devices from moisture, oxidation and other contaminants.Several chip materials are porous and amorphous and liable to absorbmoisture and contaminants, altering device performance. For example,transistor performance parameters can be changed or degraded by exposureto ionic contamination. In another aspect, sealing structures mayprotect ICs from cracks which could propagate into the chip active areaand cause circuits and devices to fail. Various sources have beenobserved from which cracks can propagate, such as from the chip siliconsubstrate, interfaces in multi-layered structures, varyingthermo-mechanical properties of multi-layered structures, and highstress processing operations such as dicing and backgrinding.

A current solution for hermetic sealing and crack stops is include ametallic sealing structure, often referred to as a seal ring, within aback-end-of-the-line (BEOL) build up structure formed over the siliconsubstrate die area. Together, the silicon substrate, seal ring, and atop passivation layer made of a material such as silicon nitride providea hermetic seal. Impermeable metal contacts can also be formed throughthe top passivation layer for electrical connection. Commonly, themetallic seal ring will be formed adjacent all sidewalls of the chip.The metal seal ring is typically formed of the same metal layers usedform interconnects and vias in the BEOL build-up structure. In additionto providing a sealing structure, the high yield stress of the metal canadditionally provide some resistance to crack propagation. Typically, aseal ring will occupy a certain width of the chip area and be spacedapart from the chip edge sidewalls by a certain buffer distance tocontain dicing damage.

SUMMARY

Chip sealing structures and methods of manufacture are described. In anembodiment, a chip structure includes a main body area formed of asubstrate, a back-end-of-the-line (BEOL) build-up structure spanningover the substrate, and chip edge sidewalls extending from a backsurface of the substrate to a top surface of the BEOL build-up structureand laterally surrounding the substrate and the BEOL build-up structure.In accordance with embodiments, conformal sealing layer may cover atleast a first chip edge sidewall of the chip edge sidewalls and aportion of the top surface of the BEOL build-up structure, and form alip around the top surface of the BEOL build-up structure.

The sealing layer may be formed on one or more, or all of the chip edgesidewalls. In an embodiment, the conformal sealing layer applies acompressive stress to the main body area, and may be characterized by ahigher coefficient of thermal expansion (CTE) than silicon. The sealinglayers may be single, or multiple layers and formed of suitablematerials including metallic material layer(s), insulating materiallayer(s), etc. In an embodiment, the conformal sealing layer does notcover a back surface of the substrate, and may form a planar surfacewith the back surface of the substrate.

The chip structures in accordance with embodiments can include singledie sets or multiple die sets, and may or may not include die-to-dierouting between the die sets. Additionally, the chip structures may alsoinclude terminal ends of die-to-die routing along the diced chip edgesidewalls.

The chip structures in accordance with embodiments, may be providedwithout requiring metallic sealing structures (e.g. seal rings) withinthe BEOL build-up structure, though can optionally be combined with suchmetallic sealing structures, including full and partial sealingstructures.

In an embodiment, a method of sealing a chip includes forming apatterning layer over a BEOL build-up structure formed over a substrate,forming an array of dicing lane grooves though the patterning layer andthrough at least a portion of the BEOL build-up structure, dicingthrough the array of dicing lane openings to form an array of kerfspartially through the substrate and define an array of main body areas,depositing a conformal sealing layer over the patterning layer, withinthe array of kerfs, and partially along a top surface of the BEOLbuild-up structure, removing the patterning layer along with a portionof the conformal sealing layer on the patterning layer and reducing athickness of the substrate to open the array of kerfs and singulate aplurality of chips.

In an embodiment, plasma dicing is used to dice through the array ofdicing lane openings to form the array of kerfs partially through theBEOL build-up structure and the substrate. In an embodiment, laserdicing is used to form the array of dicing lane grooves.

In an embodiment, openings in the patterning layer that overly the arrayof kerfs are widened prior to depositing the conformal sealing layerover the patterning layer. For example, this may be done usinglithographic techniques, and may negate the need for using multiplepatterning layers in the dicing sequence.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional side view illustration of a chipstructure including a conformal sealing layer along chip edge sidewallsin accordance with an embodiment.

FIG. 2A is a schematic cross-sectional side view illustration of a chipstructure including a conformal sealing layer along chip edge sidewallsincluding diced die-to-die routing in accordance with an embodiment.

FIG. 2B is a schematic cross-sectional side view illustration of a chipstructure including a metallic sealing structure and conformal sealinglayer along a chip edge sidewall including diced die-to-die routing inaccordance with an embodiment.

FIG. 3A is a schematic cross-sectional side view illustration of a chipstructure including a BEOL build-up structure spanning over a singleFEOL die area in accordance with an embodiment.

FIG. 3B is a schematic cross-sectional side view illustration of a chipstructure including a BEOL build-up structure spanning over multipleFEOL die areas in accordance with an embodiment.

FIG. 3C is a schematic cross-sectional side view illustration of a chipstructure including a BEOL build-up structure spanning over a pluralityof devices formed with the substrate in accordance with an embodiment.

FIG. 3D is a schematic cross-sectional side view illustration of a chipstructure including a BEOL build-up structure that includes a pluralityof devices substrate in accordance with an embodiment.

FIG. 4 is a flow chart illustrating a process for forming a plurality ofchip structures including a conformal sealing layer in accordance withan embodiment.

FIGS. 5A-5G are schematic cross-sectional side view illustrations of aprocess flow for forming a plurality of chip structures including aconformal sealing layer in accordance with an embodiment.

FIG. 6 is a schematic top view illustration of a wafer including aplurality of various die sets of different sizes in accordance with anembodiment.

FIG. 7 is a schematic cross-sectional side view illustration of aconformal sealing layer formed around individual dies in accordance withan embodiment.

FIG. 8 is a schematic top view illustration of a conformal sealing layerformed around an individual die in accordance with an embodiment.

FIG. 9 is a schematic cross-sectional side view illustration of aconformal sealing layer formed around a die set in accordance with anembodiment.

FIG. 10 is a schematic top view illustration of a conformal sealinglayer formed around an die set in accordance with an embodiment.

FIG. 11 is a schematic top view illustration of a conformal sealinglayer formed around individual dies with diced die-to-die routing inaccordance with an embodiment.

FIG. 12 is a schematic top view illustration of a conformal sealinglayer formed around an die with diced die-to-die routing in accordancewith an embodiment.

FIG. 13 is a schematic top view illustration of a conformal sealinglayer formed around a die set with diced die-to-die routing inaccordance with an embodiment.

FIG. 14 is a schematic top view illustration of a conformal sealinglayer formed around a die set with diced die-to-die routing inaccordance with an embodiment.

FIG. 15 is a schematic top view illustration of a conformal sealinglayer formed around individual dies with partial metallic sealingstructures and diced die-to-die routing in accordance with anembodiment.

FIG. 16 is a schematic top view illustration of a conformal sealinglayer formed around an die with partial metallic sealing structuresdiced die-to-die routing in accordance with an embodiment.

FIG. 17 is a schematic top view illustration of a conformal sealinglayer formed around a die set with partial metallic sealing structuresin accordance with an embodiment.

FIG. 18 is a schematic top view illustration of a conformal sealinglayer formed around a die set with partial metallic sealing structuresin accordance with an embodiment.

DETAILED DESCRIPTION

Embodiments describe chip sealing structures and methods of manufacture.In an embodiment, a chip structure includes a main body area formed of asubstrate (e.g. semiconductor substrate) such as silicon, and aback-end-of-the-line (BEOL) build-up structure spanning over thesubstrate. Chip edge sidewalls extend from a back surface of thesubstrate to a top surface of the BEOL build-up structure and laterallysurround the substrate and the BEOL build-up structure. In accordancewith embodiments, a conformal sealing layer covers at least a first chipedge sidewall of the chip edge sidewalls and a portion of the topsurface of the BEOL build-up structure to form a lip around the topsurface of the BEOL build-up structure.

In one aspect, embodiments describe conformal sealing layers that can beused in combination with or replace traditional seal ring structures.The conformal sealing layers in accordance with embodiments may alsoprovide a clamping force on the multi-layer stack, which can facilitateadhesion and sealing properties of the conformal sealing layer. Theconformal sealing layers may additionally create an impermeablemembrane.

In another aspect, the conformal sealing layers can improve chip areautilization compared to traditional seal ring structures since areacommonly reserved for seal ring physical space is removed. For example,traditional seal ring structures consume a significant die area andoverall wafer utilization, particularly for smaller dies. In accordancewith embodiment, a sidewall sealing layer allows the reduction of areaallocated to the traditional seal ring, thereby increasing the totalnumber of chips that can be harvested per wafer. Additionally, thebuffer distance from the chip edge sidewalls can be reduced by replacinghigh stress-generating mechanical dicing processes such as blade sawingwith lower stress processes. In this aspect, embodiments describeprogrammable dicing techniques. For example, this may include laserassisted chemical etch dicing flows to carve out specific die-set areas,which can also be irregularly shaped. Chemical etching may be wet etchor plasma etch, particularly if the substrate, such as a semiconductorwafer (silicon), is deep (e.g. more than 50 μm). An exemplary plasmadicing process may be, or include, a deep reactive-ion etching (DRIE)process. Such programmable dicing techniques can facilitate harvestingof arrayed structures. Furthermore, such programmable dicing techniquescan facilitate dicing through non-conventional FEOL die areas.Furthermore, such dicing techniques can be used to dice BEOL structureswith very fragile materials (e.g. dielectrics with low dielectricconstants, low-k materials) which could otherwise be damaged by highstress processes. Additionally, the sealing layers described herein canprovide added protection against processing stresses as well as sealingin the case the fragile layers are compromised.

In various embodiments, description is made with reference to figures.However, certain embodiments may be practiced without one or more ofthese specific details, or in combination with other known methods andconfigurations. In the following description, numerous specific detailsare set forth, such as specific configurations, dimensions andprocesses, etc., in order to provide a thorough understanding of theembodiments. In other instances, well-known semiconductor processes andmanufacturing techniques have not been described in particular detail inorder to not unnecessarily obscure the embodiments. Reference throughoutthis specification to “one embodiment” means that a particular feature,structure, configuration, or characteristic described in connection withthe embodiment is included in at least one embodiment. Thus, theappearances of the phrase “in one embodiment” in various placesthroughout this specification are not necessarily referring to the sameembodiment. Furthermore, the particular features, structures,configurations, or characteristics may be combined in any suitablemanner in one or more embodiments.

The terms “above”, “over”, “to”, “between”, “spanning” and “on” as usedherein may refer to a relative position of one layer with respect toother layers. One layer “above”, “over”, “spanning” or “on” anotherlayer or in “contact” with another layer may be directly in contact withthe other layer or may have one or more intervening layers. One layer“between” layers may be directly in contact with the layers or may haveone or more intervening layers.

Referring now to FIG. 1 a cross-sectional side view illustration isprovided of a chip structure 100 in accordance with an embodiment. Asshown, the chip structure 100 can include a main body area 105 formed ofa multi-layered stack including a substrate 101, a firstfront-end-of-the line (FEOL) die area 104 of a first die 106 patternedinto the substrate 101, a back-end-of-the-line (BEOL) build-up structure110 spanning over the first FEOL die area 104, and chip edge sidewalls115 extending from a back surface 102 of the substrate 101 to a topsurface 116 of the BEOL build-up structure 110 and laterally surroundingthe first FEOL die area 104 and the BEOL build-up structure 110. Inaccordance with embodiments, a conformal sealing layer 130 covers atleast a first chip edge sidewall of the chip edge sidewalls 115 and aportion of the top surface 116 of the BEOL build-up structure 110 suchthat the conformal sealing layer 130 forms a lip 134 around the topsurface 116 of the BEOL build-up structure 110.

In accordance with some embodiments, the conformal sealing layer 130material(s) may be selected to form a compressive stress to the mainbody area 105. This can be vertical stress and/or horizontal stress. Thecompressive stress can help clamp the conformal sealing layer 130 ontothe main body area and promote adhesion. Compressive stress may provideadditional protection from mechanical stressors such as cracks. Theconformal sealing layer 130 may have a sufficiently high Young'smodulus, yield stress, and fracture toughness to protect againstmechanical stressors. In an embodiment, the substrate 101 is a siliconsubstrate or silicon on insulator (SOI) substrate. The conformal sealinglayer 130 may possesses strong adhesion to silicon, and not diffusesubstantially into silicon to adversely affect device performance. In anembodiment, the conformal sealing layer 130 has a Young's Modulusgreater than silicon such as greater than 170 GPa, or more specifically300-550 GPa, such as 300-400 GPa, and a coefficient of thermal expansion(CTE) greater than the substrate (e.g. silicon), such as greater than 4ppm/° C. Compressive stress can also be tailored by depositionparameters. For example, this may be facilitated by a high temperaturedeposition process in which the deposited material contracts uponcooling, providing compressive stress. In some embodiments, theconformal sealing layer 130 may be slightly tensile, and still functionas an impermeable barrier.

The FEOL die areas 104 in accordance with embodiments can include theactive and passive devices of the dies 106. The BEOL build-up structure110 is then formed over the substrate 101 to provide electricalinterconnections. The BEOL build-up structure 110 may conventionallyfulfill the connectivity requirements of the die 106. The BEOL build-upstructure 110 may be fabricated using conventional materials includingmetallic wiring layers 114 and vias 113 (e.g. copper, aluminum, etc.)and insulating interlayer dielectrics (ILD) 111, 112 such as oxides(e.g. silicon oxide, carbon doped oxides, etc.), nitrides (e.g. siliconnitride), low-k, materials, etc. The BEOL build-up structure 110 wiringlayers 114 can be formed in lower metal layers M_low, upper metal layersM_high, and midlevel metal layers M_mid. The upper metal layers M_highmay have coarser line widths and line spacing, with the midlevel metallayers M_mid having intermediate line widths and spacing, and the lowermetal layers M_low having finer line widths and spacing. Additionally,the interlayer dielectrics (ILDs) 111 for the lower metal and midlevelmetal layers may be formed of low_k materials, which can allow quickermoisture transport. Thus, when using the finer wiring layers, additionalprecautions can be taken in accordance with embodiments, such aspassivation of diced chip edge sidewalls 115 with conformal sealinglayer 130. The top surface of the BEOL build-up structure 110 caninclude exposed contact pads 120, such as underbump metallurgy (UBM)pads, and may be connected to the FEOL die areas 104.

Up until this point, the description related to FIG. 1 has focused on achip structure 100 including a single FEOL die area 104 of a single die106. However, embodiments are not so limited and may include multipledies 106 and corresponding FEOL die areas 104, which can be connectedwith die-to-die routing within the BEOL build-up structure 110.Additionally, other structures such as metallic sealing structures (e.g.full or partial seal rings) can optionally be included within the BEOLbuild-up structure 110. Furthermore, the conformal sealing layer 130 maybe formed on any number of chip edge sidewalls 115 ranging fromselective deposition onto a single chip edge sidewall 115 or all chipedge sidewalls 115. Deposition onto multiple chip edge sidewalls 115 mayfurther facilitate clamping in the x-y plane (e.g. lateral, horizontal),with the lip 134 further facilitating clamping in the z-direction (e.g.vertical, along dicing direction).

Referring now to FIGS. 2A-2B additional illustrations are provided ofchip structures 100 with additional features. While illustrated anddescribed separately, the additional features are not necessarilyintended to be exclusive of one another, and instead are intended toillustrate flexibility for application of the conformal sealing layer130 in accordance with embodiments.

FIG. 2A is a schematic cross-sectional side view illustration of a chipstructure 100 including a conformal sealing layer 130 along chip edgesidewalls 115 similar to that illustrated and described with regard toFIG. 1 with the additional feature of diced die-to-die routing 140 inaccordance with an embodiment. As shown a terminal end 141 of thedie-to-die routing 140 may be exposed along the chip edge sidewall 115,with the conformal sealing layer 130 being deposited directly on theterminal end 141. In the embodiment illustrated, the upper metal layersM_high may be primarily used for die-to-die routing 140 for lowerresistance wiring, and possibly greater flexibility to form chipstructures 100 including custom die sets with dynamic die-to-die routing140 after testing. While the chip structure 100 of FIG. 2A includes asingle FEOL die area 104, with scribed die-to-die routing 140, the chipstructures 100 in accordance with embodiments may include a plurality ofFEOL die areas 104 corresponding to separate dies 106 connected withdie-to-die routing 140. Thus, illustration and description of FIG. 2A isnot intended to be limited to the specific structure illustrated, andinstead is intended to illustrate a chip structure 100 including aconformal sealing layer 130 deposited along a diced chip edge sidewall115 including a diced die-to-die routing 140.

Referring now to FIG. 2B, a schematic cross-sectional side viewillustration is provided of a chip structure 100 including a metallicsealing structure and conformal sealing layer 130 along a chip edgesidewall 115 including diced die-to-die routing 140 in accordance withan embodiment. Specifically, FIG. 2B illustrates a combination of apartial metallic sealing structure 152 adjacent a first chip edgesidewall 115 and a full metallic sealing structure 150 adjacent a secondchip edge sidewall 115. Full metallic sealing structures 150 may extendsubstantially through the BEOL build-up structure from underlyingsilicon substrate 101 to upper metal layers M_high and in contact withthe top passivation layer to provide an impermeable seal. Partialmetallic sealing structures 150 may include one or more openings withinthe dielectric layers 111, 112 of the BEOL build-up structure 110.

In the illustrated embodiments, the die-to-die routing 140 extendsthrough an opening 155 vertically oriented with the partial metallicsealing structure 152. Specifically, the opening 155 is illustrated asbeing above with partial metallic sealing structure 152, though theopening 155 could also be under, or within the partial metallic sealingstructure 152. In accordance with embodiments, the die-to-die routing140 can extend through multiple openings 155 within the metallic sealingstructure 152.

Still referring to FIG. 2B, some additional optional features areillustrated to show flexibility of the sealing structure designs inaccordance with embodiments. For example, where a full sealing structure150 is provided adjacent a chip edge sidewall 115, the conformal sealinglayer 130 is optionally not deposited. In the illustrated embodiment,the conformal sealing layer 130 is selectively deposited along thecompromised chip edge sidewall 115 including the partial metallicsealing structure 152. It is to be appreciated that such an embodimentis exemplary, and embodiments are not so limited.

Up until this point, the description and illustrations with regard toFIGS. 1-2B has been primarily directed to chip structures 100 includingone or more dies 106. For example, each die 106 may include a die area104 formed within the substrate 101, and overlying BEOL build-upstructure. The die area 104 may include one or more active devices (e.g.transistors for logic function) or passive devices (e.g. capacitors,inductors, resistors, etc.). Accordingly, the term “die” or “die area”as used herein can be inclusive of both active devices and passivedevices. Exemplary dies 106 can include logic, memory, and may combinemultiple intellectual property (IP) cores, or single IP cores. Forexample, the dies 106 can be system on chip (SOC) dies includingmultiple IP cores, or smaller chiplets of including one or morepartitioned IP cores. In an embodiment, the dies 106 include arrays ofpassive devices, such as capacitor arrays, for connection with otherelectronic components. In an embodiment, the chip structures 100described herein do not include a die, and instead can provide discreterouting and/or devices. For example, the chip structures 100 can be aninterfacing bar, or bridge for connecting multiple components.

Referring now to FIG. 3A a schematic cross-sectional side viewillustration is provided of a chip structure 100 including a BEOLbuild-up structure 110 spanning over a single FEOL die area 104 inaccordance with an embodiment. The single FEOL die area 104 may includemultiple devices 108, such as active device or passive devices. In anembodiment, a plurality of solder bumps 109 can be provided on the BEOLbuild-up structure 110, for example onto contact pads 120, for flip chipconnection. However, this is exemplary and embodiments are not solimited.

FIG. 3B is similar to the chip structure 100 of FIG. 3A, with theinclusion of multiple die areas 104, which can be connected bydie-to-die routing 140 in the BEOL build-up structure 110. Referring nowto FIG. 3C, a variation of FIGS. 3A-3B is illustrated in which the BEOLbuild-up structure 110 spans over a plurality of devices 108 formed inthe substrate 101. FIG. 3C is merely an alternate illustration of eitherFIG. 3A or FIG. 3B, where the plurality of devices 108 can be consideredto be in the same die area 104, or different die areas 104. Thus, FIG.3C illustrates an exemplary embodiment such as an integrated passivedevice, where a plurality of devices 108 such as trench capacitors canbe provided in a chiplet structure to be connected with anothercomponent. Referring now to FIG. 3D an alternative embodiment isillustrated where the devices 108 are optionally formed within the BEOLbuild-up structure 110 rather than in the underlying substrate 101. Insuch an embodiment, the chip structure 100 may be an interfacing bar, orbridge, including wiring layers 114, and optionally one or more devices108. In an embodiment, the chip structure 100 does not include a diearea 104. It is to be appreciated that the chip structures 100illustrated in FIGS. 3A-3D can be combined. For example, devices 108 canbe formed in both the substrate 101 and BEOL build-up structure 100,that may span over one or more die areas.

Turning now to FIG. 4 and FIGS. 5A-5G a flow chart and schematiccross-sectional side view illustrations are provided for a process offorming a plurality of chip structures including a conformal sealinglayer in accordance with an embodiment. In interest of clarity andconciseness, the flow chart provide in FIG. 4 is described concurrentlywith the illustrations in FIGS. 5A-5G. Furthermore, while the exemplaryprocess flow illustrates the formation of a plurality of chip structures100, each including a single FEOL die area 104, that the embodiments arenot so limited and may include multi-die set chip structures 100 withmultiple FEOL die areas 104, or any of the alternative chip structuresdescribed herein.

In accordance with embodiments, the combination of laser dicing andchemical etch dicing, such as plasma dicing, can be used to providecustom harvesting of various arrayed. Such programmable dicingtechniques can also be employed to provide additional flexibility intoselection of dicing areas, and to support fine dicing with reducedstreet width or loss of material. In operation, an arrayed waferincluding FEOL die areas 104 and BEOL build-up structure 110 withcomplete die-to-die routing can be received and tested for good and badFOEL die areas 104. This information is then used to create a mapidentifying valid die 106 sets for chip structures 100.

At operation 4010 a patterning layer, such as a lift-off photoresist orother masking material, is formed over the BEOL build-up structure of afully built wafer as shown in FIG. 5A using a suitable method such asspin coating. A dicing tool then retrieves the map and can performprogrammable dicing. At operation 4020 the dicing tool may first form anarray of dicing lane grooves 162 through the patterning layer 160 andthe BEOL build-up structure 110 as shown in FIG. 5B. The dicing lanegrooves 162 may be formed partially or completely through the BEOLbuild-up structure 110 to expose the substrate 101. Thus, this laserdicing operation may also cut through any die-to-die routing 140 thatmay be present in the dicing lanes. Laser cutting through the patterninglayer 160 and BEOL build-up structure 110 may avoid an additionallithography operation, and can be well defined (e.g. <1 μm edge). Atoperation 4030 dicing is then performed through the array of dicing laneopenings to form an array of kerfs 164 partially through the underlyingsubstrate 101 as shown in FIG. 5C. In accordance with embodiments, thisoperation may be a chemical etch dicing operation such as plasma dicingor wet chemical dicing, using the patterning layer 160 as an etch mask.The chemical etch dicing operation may additionally define a pluralityof main body areas 105 in the multi-layer stack-up, including what willbecome the chip edge sidewalls 115. Such programmable dicing techniquesas described with operations 4020-4030 can be used to achieve finedicing, with mitigated material loss. This facilitates integration ofdense arrayed structures. Additionally, the programmable dicingtechniques are very flexible for shape, size or layout constraints. Thisallows the freedom to dice chip structures with die sets of any shape.This ability thus allows additional reliability margin improvements tothe diced die sets to be realized with programmable dicing in accordancewith embodiments.

Referring now to FIG. 5D openings 166 in the patterning layer 160 thatoverlie the array kerfs 164 are widened. For example, the openingspreviously corresponding to formation of the dicing lane grooves 162 andsubsequent kerfs 164 are further widened within the patterning layer160. This may correspond to a resist pull-back operation in whichlithography is used to pattern the opening 166. This is followed withoperation 4040 in which a conformal sealing layer 130 is deposited overthe patterning layer 160, within the array of kerfs 164, and partiallyalong the top surface 116 of the BEOL build-up structure 110 to formlips 134. As shown, the conformal sealing layer 130 is deposited alongthe chip edge sidewalls 115 and bottom surface 165 of the kerfs 164within the substrate 101. In accordance with embodiments, the conformalsealing layer 130 may be a single layer or include multiple layers.

The conformal sealing layer 130 may be formed of a variety of materials,or layer stacks of different materials, including semiconductors,metals, semi-metals, dielectrics, ceramics, and polymers. Selection ofmaterial may be based on at least barrier properties, clamping action,and diffusivity into the substrate, with higher Young's Modulus and CTEtending to provide higher clamping action. A listing of exemplarymaterials is provided in Table 1.

TABLE 1 Listing of conformal sealing layer exemplary materials Young'sCTE Diffusivity Material Modulus (ppm/ Barrier Clamping risk in ClassMaterial (GPa) ° C.) properties action silicon Comment Semi- Si 170 3conductors Metals/ TiN 500 9 Good Good Low Film may apply Semi-bidirectional metals compressive stress Ti 120 9 Good, also Good HighSilicide a getter formation with for Si may help oxidation adhesion andmoisture Cu 130 17 Good Good High Dielectrics SiO2 80 0.5 ModerateModerate Low SiO2 is weaker (Glass) and may be under tensile stressSi—O—C—N ~100 ~3 Moderate+ Moderate+ Low Better alloys than SiO2Ceramics SiN 350 1 Good Moderate+ Low Al2O3 450 4.5 Good Good LowPolymers Polyimide 2.5 50 Moderate Moderate Low

In accordance with embodiments, the conformal sealing layer 130 mayexert a compressive stress on the main body areas 105. This can bevertical stress and/or horizontal stress in the vicinity of the sealinglayer. The compressive stress can help clamp the conformal sealing layer130 onto the main body area and promote adhesion. The vertical stresscan also help hold the stack together. For example, this may befacilitated by a high temperature deposition process in which thedeposited material contracts upon cooling, providing compressive stress.The conformal sealing layer 130 may be formed of suitable materials,including oxides (e.g. alumina), nitrides (e.g. silicon nitride,titanium nitride, titanium carbonitride, chromium nitride, aluminumtitanium nitride, aluminum titanium chromium nitride, zirconiumnitride), metals, and metal oxides. Suitable deposition methods include,but are not limited to, chemical vapor deposition (CVD), plasma enhancedchemical vapor deposition (PECVD), atomic layer deposition (ALD), andphysical vapor deposition (PVD). In an embodiment, the conformal sealinglayer 130 has a Young's Modulus greater than silicon such as greaterthan 170 GPa, or more specifically 300-400 GPa, and a coefficient ofthermal expansion (CTE) greater than silicon, such as greater than 4ppm/° C.

Following deposition of the conformal sealing layer 130, the patterninglayer 160 may then be removed along with a portion of the conformalsealing layer 130 on top of the patterning layer 160 at operation 4050,and as shown in FIG. 5F. The multi-layer stack may then be flipped over,and a thickness of the substrate 101 is reduced to open up the array ofkerfs 164 at operation 4060, which also has the effect of singulatingthe plurality of chip structures 100 as shown in FIG. 5G. The reductionin thickness can be performed chemically, or through a backgrindingoperation such as chemical mechanical polishing (CMP) where the depth ofthe back surface 102 is reduced past the bottom surfaces 165 of thekerfs 164. As a result, the back surfaces 102 of the substrate 101 mayform a planar surface with back surfaces 137 of the conformal sealinglayer 130.

Referring now to FIG. 6 , a schematic top view illustration is providedof a wafer (substrate 101) including a plurality of various FEOL dieareas 104 arranged in die 106 sets of different sizes in accordance withan embodiment. Specifically, FIG. 6 illustrates an exemplary stage inprocessing similar to FIG. 5F, after deposition of a conformal sealinglayer 130 and prior to backgrinding to singulate each chip structure100. It is to be appreciated that the illustration provided in FIG. 6however shows conformal sealing layer 130 outlines, generally as theymay appear after singulation in order to show dicing lanes between chipstructures 100.

As shown, adjacent FEOL die areas 104 can be interconnected withdie-to-die routing 140 to form chip structures 100 with any number ofdie sets. Specifically illustrated are die sets of 1X, 2X, 4X, 8X. EachFEOL die area 104 may have a distinct circuit block separate fromadjacent die areas 104. Each FEOL die area 104 may represent a completesystem, or sub-system. Adjacent FEOL die areas 104 may perform the sameor different function. In an embodiment, an FEOL die area 104interconnected with die-to-die routing can include a digital die areatied to an FEOL die area 104 with another function, such as analog,wireless (e.g. radio frequency, RF) or wireless input/output, by way ofnon-limiting examples. The tied FEOL die areas 104 may be formed usingthe same processing nodes, whether or not having the same or differentfunctions. Whether each FEOL die area 104 includes a complete system, orare tied subsystems, the die-to-die routing 140 may be inter-die routing(different systems) or intra-die routing (different, or same subsystemswithin the same system). For example, intra die-to-die routing mayconnect different subsystems within a system on chip (SOC) where interdie-to-die routing can connect different SOCs, though this isillustrative and embodiments are not limited to SOCs.

In accordance with embodiments, any or all FEOL die area 104 edges canbe configured to include die-to-die routing 140. As shown in FIG. 6 ,dicing or scribe lanes can be located anywhere to accommodate yield(e.g. bad dies) or demand (e.g. need for larger die sets. Dicing can beperformed through die-to-die routing 140 between FEOL die areas 104, ornot. For example, the top five rows on substrate 101 are illustrated ashaving selective conformal sealing layers 130 deposited aroundpre-determined chip structure 100 die sets. The specific die 106 setscould have been determined after initial die area testing prior tocompleting the die-to-die routing 140, or after completion of the BEOLbuild-up structures including die-to-die routing 140. A defective FEOLdie area, marked with an “X,” may cause dicing to be performed throughdie-to-die routing 140 which would have otherwise connected adjacent dieareas 104 within a chip structure 110. The bottom two rows show aslightly different configuration, where die-to-die routing 140 connectsall FEOL die areas 104 in the bottom two rows, and die set determinationis made after formation of the die-to-die routing. In thisconfiguration, dicing lanes will go through die-to-die routing 140. Theharvesting and chip sealing techniques in accordance with embodimentscan facilitate improved wafer utilization and harvesting of more dies orcomponents. For example, this may be accomplished by being able toharvest die sets of different or irregular shapes, as well as utilizingprogrammable dicing methods.

In order to illustrate flexibility of the conformal sealing layer 130and programmable dicing methods, various exemplary implementations aredescribed and illustrated with regard to FIGS. 7-18 . It is to beappreciated that the following examples are illustrative of differentfeatures, and are not necessarily restrictive of one another, and may becombined in various single and multiple die set arrangements. Similar toFIG. 6 , FIGS. 7-18 illustrate exemplary embodiments after deposition ofa conformal sealing layer 130, and prior to backgrinding.

Referring to FIGS. 7-8 , FIG. 7 is a schematic cross-sectional side viewillustration of a conformal sealing layer 130 formed around individualdies 106 in accordance with an embodiment. FIG. 8 is a schematic topview illustration of a conformal sealing layer formed around anindividual die 106 in accordance with an embodiment. Thus, theembodiments illustrated in FIGS. 7-8 may correspond to sealing of a chipstructure 100 including a 1X die set of FIG. 6 . More specifically, thecross-sectional side view illustration of FIG. 7 illustrates variouswiring layers M_low, M_mid, M_high, optionally a multiple layerconformal sealing layer 130 including a first seal layer 131 formedalong chip edge sidewalls 115 and top surface 116 of the BEOL build-upstructure 110, and second seal layer 132 formed on the first seal layer131. In the exemplary top view illustration of FIG. 8 , the chipstructure 100 includes a FEOL die area 104 that includes both a devicearea 170 and input output/region(s) 172. In an exemplary implementation,die routing 174 within the BEOL build-up structure 110 may be connectedto the input/output region(s) 172 for potential connection to die-to-dierouting. For example, the die routing 174 may be included within one ofthe upper metal layers, M_high, and connected to the FEOL die area 104with various wiring layers 114 and vias 113 (see FIG. 1 ). In theexemplary embodiment illustrated, the chip structure 100 does notinclude die-to-die routing.

Referring to FIGS. 9-10 , FIG. 9 is a schematic cross-sectional sideview illustration of a conformal sealing layer 130 formed around a die106 set in accordance with an embodiment. FIG. 10 is a schematic topview illustration of a conformal sealing layer formed around a die setin accordance with an embodiment. As shown, the chip structures 100 caninclude internal die-to-die routing 140 connecting the adjacent dies106. Thus, the embodiments illustrated in FIGS. 9-10 may correspond tosealing of a chip structure 100 including a 2X die set similar to thatillustrated in FIG. 6 .

Referring to FIGS. 11-12 , FIG. 11 is a schematic top view illustrationof a conformal sealing layer 130 formed around individual dies 106 withdiced die-to-die routing 140 in accordance with an embodiment. FIG. 12is a schematic top view illustration of a conformal sealing layer formedaround a die 106 with diced die-to-die routing 140 in accordance with anembodiment. The embodiments illustrated in FIGS. 11-12 may correspond tosealing of a chip structure 100 including a 1X′ die set similar to thatillustrated in FIG. 6 .

Referring to FIGS. 13-14 , FIG. 13 is a schematic top view illustrationof a conformal sealing layer 130 formed around a die 106 set with diceddie-to-die routing 140 in accordance with an embodiment. FIG. 14 is aschematic top view illustration of a conformal sealing layer formedaround a die set with diced die-to-die routing in accordance with anembodiment. The embodiments illustrated in FIGS. 13-14 may correspond tosealing of a chip structure 100 including a 2X′ die set similar to thatillustrated in FIG. 6 .

Referring to FIGS. 15-16 , FIG. 15 is a schematic top view illustrationof a conformal sealing layer 130 formed around individual dies 106 withpartial metallic sealing structures 152 and diced die-to-die routing 140in accordance with an embodiment. FIG. 16 is a schematic top viewillustration of a conformal sealing layer formed around an die withpartial metallic sealing structures 152 diced die-to-die routing 140 inaccordance with an embodiment. In particular, FIGS. 15-16 illustrate thecompatibility of the conformal sealing layer 130 with compromised, orpartial metallic sealing structures 152 in accordance with embodiments.Full metallic sealing structures 150 can also be included. As shown,partial metallic sealing structures 152 can be formed partially or fullyaround the dies 106, with die-to-die routing 140 completed for desireddie sets. Partial metallic sealing structures 152 can be incorporated toprovide design flexibility for harvesting interconnected die sets, whilefull metallic sealing structure 150 can be incorporated to provide morerobust physical and/or electrical protection to the die within a chipstructure 100. The conformal sealing layer 130 can fully seal the chipedges sidewalls 115 adjacent the partial metallic sealing structures152.

Referring to FIGS. 17-18 , FIG. 17 is a schematic top view illustrationof a conformal sealing layer 130 formed around a die 106 set withpartial metallic sealing structure 152 in accordance with an embodiment.FIG. 18 is a schematic top view illustration of a conformal sealinglayer formed around a die set with partial metallic sealing structure152 in accordance with an embodiment. FIGS. 17-18 are substantiallysimilar to those illustrated in FIGS. 15-16 , with a difference beingthat dicing is not performed through the die-to-die routing 140.Similarly, the conformal sealing layer 130 can fully seal the chip edgessidewalls 115 adjacent the partial metallic sealing structures 152.

While not separately illustrated, it is to be appreciated that theconformal sealing layer 130 of FIGS. 17-18 can be formed along a single,multiple, or all chip edge sidewalls 115. For example, where an internalfull metallic seal structure 150 is located adjacent a chip edgesidewall 115, the conformal sealing layer 130 is optional.

In utilizing the various aspects of the embodiments, it would becomeapparent to one skilled in the art that combinations or variations ofthe above embodiments are possible for forming sealed chip structure.Although the embodiments have been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the appended claims are not necessarily limited to the specificfeatures or acts described. The specific features and acts disclosed areinstead to be understood as embodiments of the claims useful forillustration.

What is claimed is:
 1. A chip structure comprising: a main body areaincluding: a substrate including a front side and a back surfaceopposite the front side; a back-end-of-the-line (BEOL) build-upstructure spanning over the front side of the substrate; chip edgesidewalls extending from a back surface of the substrate to a topsurface of the BEOL build-up structure and laterally surrounding thesubstrate and the BEOL build-up structure; and a conformal sealing layercovering at least a first chip edge sidewall of the chip edge sidewallsfrom the back surface of the substrate to the top surface of the BEOLbuild-up structure and a portion of the top surface of the BEOL build-upstructure, wherein the conformal sealing layer forms a lip around thetop surface of the BEOL build-up structure.
 2. The chip structure ofclaim 1, wherein the conformal sealing layer covers all of the chip edgesidewalls.
 3. The chip structure of claim 1, wherein the conformalsealing layer applies a compressive stress to the main body area.
 4. Thechip structure of claim 1, wherein the substrate comprises silicon, andthe conformal sealing layer is characterized by a higher coefficient ofthermal expansion (CTE) than silicon.
 5. The chip structure of claim 1,wherein the BEOL build-up structure does not include a metallic sealingstructure.
 6. The chip structure of claim 1, wherein further comprisinga plurality of devices formed in the BEOL build-up structure.
 7. Thechip structure of claim 1, wherein the substrate is a semiconductorsubstrate, and further comprising a first front end of the line (FEOL)die area of a first die patterned into the semiconductor substrate. 8.The chip structure of claim 7, wherein the first FEOL die area includesa plurality of passive devices.
 9. The chip structure of claim 7,wherein the first FEOL die area includes a plurality of active devices.10. The chip structure of claim 7, wherein the BEOL build-up structurecomprises a die-to-die routing connected between the first FEOL die areaand a terminal end of the die-to-die routing at the first chip edgesidewall.
 11. The chip structure of claim 10, wherein the BEOL build-upstructure includes a metallic sealing structure, and the die-to-dierouting extends through an opening vertically oriented with the metallicsealing structure.
 12. The chip structure of claim 7: further comprisinga second FEOL die area of a second die patterned into the semiconductorsubstrate; wherein the BEOL build-up structure spans over the secondFEOL die area; and wherein the chip edge sidewalls laterally surroundthe first FEOL die area, the second FEOL die area, and the BEOL build-upstructure.
 13. The chip structure of claim 12, wherein the BEOL build-upstructure further comprises a die-to-die routing connecting the firstFEOL die area and the second FEOL die area.
 14. The chip structure ofclaim 13, wherein the BEOL build-up structure further comprises a seconddie-to-die routing connected between first FEOL die area and a terminalend of the second die-to-die routing at the chip edge sidewall.
 15. Thechip structure of claim 1, wherein the conformal sealing layer does notcover the back surface of the substrate.
 16. The chip structure of claim15, wherein the conformal sealing layer comprises a metallic layer. 17.The chip structure of claim 15, wherein the conformal sealing layercomprises an insulating material layer.
 18. The chip structure of claim1, wherein the back surface of the substrate and the conformal sealinglayer form a planar surface.